Collapsible containers, drinking cups and the like are, of course, well known. For example, in applicant's own prior U.S. Pat. No. 4,930,644, a collapsible, thin film plastic container is disclosed wherein a major portion of the container side wall has a reduced wall thickness to permit random collapse of the side wall. In U.S. Pat. 4,865,211, a plastic bottle having a uniform wall thickness throughout the side wall, is configured to permit collapsing of the container through telescoping movement of one portion of the side wall into another portion of the side wall.
In U.S. Pat. 4,875,576, a container is disclosed wherein an intermediate portion of the side wall incorporates a bellows-type arrangement for facilitating collapse and extension of the container. The patent also discloses the use of helical creases which spiral or angle between first and second portions of the container side wall to facilitate collapsing action of the creased portion of the side wall.
In U.S. Pat. No. 4,873,100, a bi-stable, expandable plastic bottle is disclosed which incorporates bellows-type side wall for movement between collapsed and extended positions.
In U.S. Pat. No. 2,880,902, a collapsible drinking cup (or camera bellows) is disclosed wherein the side wall is composed of alternating thick and thin portions.
In U.S. Pat. Nos. 5,226,551 and 5,417,337, there are disclosed a variety of collapsible plastic containers incorporating peripheral side walls usually having at least three axial sections including an upper section, an intermediate section and a lower section. The intermediate section has a significantly reduced wall thickness permitting the lower section to be pushed upwardly into the upper section with the intermediate section reverse folded therebetween. In addition, the diameters of the intermediate section and at least part of the lower section are smaller than the upper section to facilitate the folding or collapsing process.
Of particular concern in collapsible container construction are the transition areas (or annular fold lines) between adjacent thick and thin sections of the peripheral side wall. This is because these areas often determine the ease or difficulty with which the collapsing/folding action is initiated. In addition, prior constructions have not been completely satisfactory in that cracking and fracture of the polymer can occur at the annular fold lines upon repeated collapsing and expansion movements. It will be appreciated that consumer acceptance depends on reliability, ease of use, cost, etc., and therefore, concerns about ease of use, reliability and durability must be addressed satisfactorily.